This invention relates to control valves for fluid operated clutches or the like as, for example, employed in marine propulsion systems.
Prior art of possible relevance includes the following U.S. Pat. Nos. 3,752,281 issued Aug. 14, 1973 to Arnold; and 3,872,956 issued Mar. 25, 1975 to Herr et al.
In certain propulsion systems as, for example, marine drive propulsion systems, one engine is employed to provide motive power as well as to power auxiliary equipment. Frequently, a need arises for a relatively low propulsion drive speed coupled with a need for a relatively high propulsion engine speed for the purpose of driving the auxiliary equipment at a relatively higher speed. Frequently, also, there arises a need for precise control of motive power speed at a constant value.
Typically, fluid operated clutches are utilized and allow varying degrees of slippage between the engine and the motive output, the degree of slippage being controlled to achieve the desired motive output speed. In typical fluid operated clutches utilized for the purpose, the capacity of the clutch is typically regulated by modulating the flow of operating fluid to the clutch. Many systems for modulating the flow of fluid to the clutch are extremely cumbersome and expensive and difficult to maintain. Frequently, they are contained within the clutch unit itself and are not susceptible to easy access for maintenance. In addition, such control systems are not subject to installation in an already existing propulsion system including a fluid operated clutch, thereby requiring the purchase of an entire drive and control system when only the control system may be needed.